Nanoparticles can be used as delivery vehicles for therapeutic and imaging agents to provide improved biodistribution and increased delivery efficiency of the agents to cell or tissue (e.g., solid tumors) in a subject. Advantageously, nanoparticles with more than one function can be designed that target, image, and destroy tumors. These multifunctional nanoparticles can be formed from, for example, liposomes, dendrimers, other lipidic and polymeric nanoparticles, and metal nanoparticles (e.g., iron oxide and gold). While the shape of the majority of these particles is spherical due to the methods of preparation, oblate- and rod-shaped nanostructures suitable for biomedical applications, such as gold nanorods, nanoworms, and nanonecklaces, have recently been fabricated. For example, nanoworms consist of iron oxide cores aligned along strands of high-molecular weight dextran. A nanonecklace was formed by attaching monofunctionalized gold nanoparticles onto polylysine.